[llvm-dev] Debug info error on bitcode inline modification

[Ku Nanashi via llvm-dev]

Hi,

I'm trying to inline function defined in another bitcode module via bitcode
modification.
I'm linking multiple bitcode modules, setting inline related attributes,
applying -always-inline pass, but then debug info error occurs.
It seems debug info metadata isn't properly updated on inlining. How can I
fix it?
I'm using LLVM 3.8.1 on OS X (On below example target is Android but it
should be same on others).
I'll appreciate any advice. Thanks.

* Targets
caller.cpp
-----------------------------------------------------------------
#include <android/log.h>

#ifdef __cplusplus
extern "C" {
#endif

void caller()
{
        __android_log_print(ANDROID_LOG_DEBUG, "TEST", "%s:%d:%s",
__FILE__, __LINE__, __FUNCTION__);
}

#ifdef __cplusplus
}
#endif
-----------------------------------------------------------------

callee.cpp
-----------------------------------------------------------------
#include <android/log.h>

#ifdef __cplusplus
extern "C" {
#endif

void callee()
{
        __android_log_print(ANDROID_LOG_DEBUG, "TEST", "%s:%d:%s",
__FILE__, __LINE__, __FUNCTION__);
}

#ifdef __cplusplus
}
#endif
-----------------------------------------------------------------

* Building bitcode
-----------------------------------------------------------------
$ clang++ (...snip target specific flags...) -emit-llvm caller.cpp -o
caller.bc
$ clang++ (...snip target specific flags...) -emit-llvm callee.cpp -o
callee.bc
-----------------------------------------------------------------

* Linking bitcode
-----------------------------------------------------------------
$ llvm-link caller.o callee.o -o=test.bc
-----------------------------------------------------------------

* Modifying bitcode
inliner.cpp
-----------------------------------------------------------------
#include "llvm/IR/Type.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

int main(int argc, char *argv[])
{
        SMDiagnostic error;
        LLVMContext context;
        Module *M = parseIRFile(argv[1], error, context).release();

        for (Module::iterator F = M->getFunctionList().begin(); F !=
M->getFunctionList().end(); F++)
        {
                if (!F->isDeclaration())
                {
                        if (F->getName() == "caller")
                        {
                                Function* callee = M->getFunction("callee");

                                inst_iterator I = inst_begin((Function *)F);
                                Instruction *inst = &*I;

                                CallInst::Create(callee, "", inst);
                        }

                        if (F->getName() == "callee")
                        {
                                F->setLinkage(GlobalValue::InternalLinkage);
                                F->addFnAttr(Attribute::AlwaysInline);
                                F->addFnAttr(Attribute::InlineHint);
                        }
                }
        }

        std::error_code ec;
        raw_fd_ostream os(argv[1], ec, sys::fs::F_None);
        WriteBitcodeToFile(M, os);
}
-----------------------------------------------------------------

-----------------------------------------------------------------
$ g++ (...snip host specific flags...) inliner.cpp -o inliner
$ ./inliner test.bc
-----------------------------------------------------------------

* Applying -always-inline pass (Debug info error occurs)
-----------------------------------------------------------------
$ opt -debug-pass=Structure -always-inline test.bc -o test.bc.inline
Pass Arguments:  -targetlibinfo -tti -assumption-cache-tracker -basiccg
-always-inline -verify
Target Library Information
Target Transform Information
Assumption Cache Tracker
  ModulePass Manager
    CallGraph Construction
    Call Graph SCC Pass Manager
      Inliner for always_inline functions
      FunctionPass Manager
        Module Verifier
    Bitcode Writer
!dbg attachment points at wrong subprogram for function
!16 = distinct !DISubprogram(name: "caller", scope: !1, file: !1, line: 11,
type: !17, isLocal: false, isDefinition: true, scopeLine: 12, flags:
DIFlagPrototyped, isOptimized: true, variables: !19)
void ()* @caller
  %call.i = call i32 (i32, i8*, i8*, ...) @__android_log_print(i32 3, i8*
getelementptr inbounds ([5 x i8], [5 x i8]* @.str.3, i32 0, i32 0), i8*
getelementptr inbounds ([9 x i8], [9 x i8]* @.str.1.4, i32 0, i32 0), i8*
getelementptr inbounds ([111 x i8], [111 x i8]* @.str.2.5, i32 0, i32 0),
i32 13, i8* getelementptr inbounds ([7 x i8], [7 x i8]*
@__FUNCTION__.callee, i32 0, i32 0)) #2, !dbg !30
!30 = !DILocation(line: 13, column: 2, scope: !23)
!23 = distinct !DISubprogram(name: "callee", scope: !21, file: !21, line:
11, type: !17, isLocal: false, isDefinition: true, scopeLine: 12, flags:
DIFlagPrototyped, isOptimized: true, variables: !19)
!23 = distinct !DISubprogram(name: "callee", scope: !21, file: !21, line:
11, type: !17, isLocal: false, isDefinition: true, scopeLine: 12, flags:
DIFlagPrototyped, isOptimized: true, variables: !19)
LLVM ERROR: Broken function found, compilation aborted!
-----------------------------------------------------------------

If I add -strip-debug pass, no error occurs, but of course debug info is
lost...
-----------------------------------------------------------------
$ opt -debug-pass=Structure -strip-debug -always-inline test.bc -o
test.bc.inline
Pass Arguments:  -targetlibinfo -tti -assumption-cache-tracker -basiccg
-always-inline -verify
Target Library Information
Target Transform Information
Assumption Cache Tracker
  ModulePass Manager
    CallGraph Construction
    Call Graph SCC Pass Manager
      Inliner for always_inline functions
      FunctionPass Manager
        Module Verifier
    Bitcode Writer
-----------------------------------------------------------------
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